The present invention relates to a thermal analysis apparatus in which a sample is heated and a physical change of the sample following upon a temperature change is measured.
From olden times, as a method of evaluating a temperature characteristic of the sample, there is performed a method called a thermal analysis in which the sample is heated and the physical change of the sample following upon the temperature change is measured. As the thermal analysis like this, from its object, although various methods are proposed, there are, e.g., a differential thermal analysis in which the sample and a reference material are heated while being juxtaposed and a relative change in a temperature is measured, a thermogravimetric analysis in which a weight change of the sample following upon the temperature change is measured, and the like.
For example, as an apparatus for performing the thermogravimetric analysis, there is proposed a thermal analysis apparatus having possessed a furnace tube which is like a cylinder and in whose inside there is formed a sample chamber, a heating furnace which is surrounded by a side face of the furnace tube and heats the sample chamber through the furnace tube, a sample holding part which holds the sample, a thermocouple which is provided in the sample holding part and detects a temperature of the sample, and a weight detector which is provided in the sample holding part and can measure the weight change of the sample (e.g., refer to Patent Document 1). In the thermal analysis apparatus like this, by inserting the sample having been held by the sample holding part into an inside of the furnace tube, heating it by the heating furnace, measuring the temperature of the sample by the thermocouple, and measuring a weight of the sample by the weight detector, it is deemed that the weight change of the sample following upon the temperature change can be measured.
Further, in recent years, there are also proposed a thermal analysis apparatus in which the thermogravimetric analysis is performed like the above by additionally providing, together with the sample holding part like this, which holds the sample, a separate sample holding part which holds the reference material, and a separate thermocouple which measures a temperature of the reference material, and in which the differential thermal analysis can be performed as well by measuring a relative change in temperatures of the sample and the reference material, and the like.
[Patent Document 1] JP-A-11-326249 Gazette
However, in such a thermal analysis apparatus as shown in the Patent Document 1, when heating the sample by being inserted into the inside of the furnace tube, also the furnace tube expands or contracts following upon the temperature change. Therefore, the sample having been disposed in the inside of the furnace tube changes in its relative position in an axial direction and a radial direction of the furnace tube following upon the temperature change of the furnace tube. While an inside of the furnace tube having been heated by the heating furnace is uniform in its temperature distribution in the axial direction, in the radial direction it has a steep temperature distribution toward a center. Therefore, in a case where the furnace tube has position-deviated in the radial direction, there has been a problem that a heating environment of the sample changes, so that a precise measurement becomes impossible to be performed.
This invention is one having been made in view of the circumstances having been mentioned above, and one providing a thermal analysis apparatus in which there is no fact that, when heating the sample, the furnace tube position-deviates due to the temperature change, and the thermal analysis can be performed by heating the sample always in a constant heating environment.